Stop-mechanism for document copier

ABSTRACT

A stop-mechanism is disclosed for use with a document feeder which itself supplies documents to-be-copied onto a glass top. The stop-mechanism includes a flag which is disposed in contact with the glass top of the copy machine and which is actuated by the document to-be-copied as it is discharged onto the glass top of the copier by the document feeder.

BACKGROUND OF THE INVENTION

The present invention relates to document copying devices andparticularly to sheet-feeding mechanism for advancing, seriatim, theindividual sheets from a stack of sheets to be copied.

The stack of sheets is placed on a holder, and the mechanismautomatically feeds the bottom-most sheet onto the copier, on demand, asthe copier operates.

In the past, sheet-feeding mechanisms have generally been large, bulky,and heavy, supported to one side of the copying surface on or adjacentthe frame of the copier, with complicated drive-mechanism to interactbetween the sheet-feeder and the copier when the sheet-to-be-copied isadvanced to the copy position of the copier.

Illustrative of the type of document feeders known in the past is thatshown in FIG. 12 herein, as well as in my own U.S. patent applicationSer. No. 559,081 filed Dec. 7, 1983 (now continuation-in-partapplication Ser. No. 755,682 filed July 16, 1985. See also British Pat.No. 922,780 and U.S. Pat. No. 4,368,881.

SUMMARY OF THE PRESENT INVENTION

In the present invention, the document feeder is a compact, box-likeunit which rests directly upon the glass plate copying surface of thecopy machines. It can be used with copiers having a stationary copyingsurface or those having a reciprocating copying surface. It is to beunderstood that the copying machines, which may be well-known officecopiers, facsimile, or electronic mail copiers, (as well as the copieswhich are made thereby), are not a part of this invention.

The document feeder has a cover which also functions as a tray-supportfor the documents to be copied. When the operator chooses to use thedocument feeder, the box is placed directly upon the glass plate of thecopy machine and the cover is raised into an inclined support-positionfor the documents.

The set of documents to be copied is placed face-up on the inclinedsupport with the first page on the top, and with the bottom (or last)page of the document, as it rests on the tray, coming into contact witha feed roller of the feeder.

Upon command, the feed roller rotates to remove the bottom sheet of thedocument from the tray support and (in cooperation with a drive-wheel)transfers it face-down onto the glass plate of the copier.

After the document has been copied, and while the copier is re-cycling,the drive wheel reverses direction, removes the document from the glassplate and transfers it face-up into a document-receiving tray.

During the next cycle, the drive wheel reverses and brings the nextsheet from the stack of documents onto the glass plate, and the sequenceis repeated.

After all the sheets have been copied, the documents may be removed fromthe receiving tray, the document support can be lowered to its positionas a cover for the feeder, and the feeder may be removed from the copymachine.

The copier discharges the newly-made copy face-up into itscopy-receiving tray and, therefore, the new set of copies are in order,when finished, with the top page on top.

Inasmuch as the newly-prepared copies, as well as the re-stacked set ofcopied documents are discharged from the copier face-up, all copies anddocuments are in proper sequence with the first page at the top of thestack and re-stacking is not required.

The document feeder of the present invention is lightweight, simple anduncomplicated and can be manufactured inexpensively and sold at areasonable price. It can be used with a copier by an inexperiencedoperator and does not need a skilled service person for installation oroperation.

The principle object of the present invention is to provide a documentfeeder which is small, compact, high-speed, easily transported,lightweight, and inexpensive.

A further object of the present invention is to provide a documentfeeder which can be used with any standard and well-known copy machinehaving either a stationary glass plate or a reciprocating glass plate.

Another object is to provide a low-cost feeder which can be easilyconnected to the copier so that the operation of the feeder may beautomatically controlled from the control panel of the copier.

With the above and other objects in view, more information and a betterunderstanding of the present invention may be achieved by reference tothe following detailed description.

DETAILED DESCRIPTION

For the purpose of illustrating the invention, there is shown in theaccompanying drawings a form thereof which is at present preferred,although it is to be understood that the several instrumentalities ofwhich the invention consists can be variously arranged and organized andthat the invention is not limited to the precise arrangements andorganizations of the instrumentalities as herein shown and described.

In the drawings, wherein like reference characters indicate like parts:

FIG. 1 is a top perspective view of the document feeder of the presentinvention.

FIG. 2 is another top perspective view of the document feeder of thepresent invention with the document support tray in elevated position.

FIG. 3 is a schematic side elevational view of the document feedershowing the sheet-path through the feeder mechanism.

FIG. 4 is a plan view of the document feeder on a copier, showing aflange to cover the unused portion of the glass and to position thedocument feeder.

FIG. 5 is a schematic illustration of the sheet-advancing feed wheels.

FIG. 6 is a schematic illustration of the forces acting on the sheets.

FIG. 7 is a greatly enlarged diagram of the frictional forces actingupon the sheets.

FIG. 8 is a schematic illustration of an alternate feed/sheet separatormechanism.

FIG. 9 is a schematic drawing of the power-train or drive-mechanism ofthe present invention.

FIG. 10 is a side elevation of a section as shown generally at 10--10 ofFIG. 9.

FIG. 11 is a fragmentary cross-section shown generally at 11--11 in FIG.4.

FIG. 12 is an illustration of a prior-art feeder.

FIG. 13 is a vertical schematic drawing of one form of paper-stop.

FIG. 14 is a vertical schematic view of another form of paper-stop.

FIG. 15 is a vertical cross-sectional view of one form of drive-wheeltaken along lines 15--15 of FIG. 9.

FIG. 16 is a cross-sectional view taken generally along line 16--16 ofFIG. 15.

FIG. 17 is a fragmentary front elevational view of a light-weight pivotarm for a paper-stop.

FIG. 18 is a vertical sectional view taken generally along line 18--18of FIG. 17.

In the present invention, a feeder 21 of generally box-likeconfiguration has a body 22 and a top 23 (shown open at 23-a and closedat 23-b). The body 22 has a bottom 24 which is a generally rectangularframe having side portions 25 and an opening 26-a(FIGS. 4 and 11)

The bottom portion 24 is designed to be placed upon the glass plate of acopy machine, but supported above the copier glass to provide a thinspace 26-a of appropriate size between glass and feeder for a documentto be received therein.

The top 23 is pivoted at 23-c so that it can tilt to the position shownin FIGS. 2 and 3, and thus provide an inclined document-support 23-a fora stack of documents 28.

As many as twenty of more documents can be supported face-up on the tray23-a and the bottom sheet 30 of the stack of documents 28 comes intocontact with a feed roller 31, disposed along a generally central lineof the stack of documents. This arrangement eliminates drive wheels andseparators near the edges of the documents which, in many cases, may bedamaged or wrinkled or otherwise rendered unsuitable for easy separationand feeding of the documents.

The preferred embodiment may be inter-connected with the copier in sucha way that the required few watts of the low-voltage power and timing(logic) may be derived directly from the copier. Alternatively, thefeeder of the present invention may have its own logic. Power may besupplied from a wall outlet mounted transformer, the copier, orrechargeable batteries. If desirable, the unit can be powered by adry-cell battery arrangement which would provide the lowest cost of anon-interfaced design.

Additionally, the size of the trays and supports and guides may beappropriately chosen for U.S.-size paper, or for the international size(DIN-A4) used generally elsewhere around the world, or legal-size paper(81/2"×13" or 81/2"×14").

Because the feeder can be easily removed from the copier, the copier canbe used without the automatic document feeder of the present invention.

After the document feeder 21 of the present invention is placed upon thecopier 102 in alignment with the registration edge 118, and the tray 23is elevated to support-position 23-a, the stack 28 of sheets to becopied is placed upon the tray 23, face-up. The feeder 21 is resting onthe copier glass 112 and positioned by flange 100.

When the copy machine is started, the document feeder is also actuated,either by its own power and logic (in synchronism with the copier) or asinstructed by the power and logic of the copier if connected thereto.Then the feed wheel 31 is caused to rotate in the direction of the arrow32, moving the bottom sheet 30 from the stack 28 around the periphery ofthe wheel 51 and onto the top of the glass plate 112 in the thin space26-a until it reaches the stop or abutment 34. At this moment, the sheetis in position to be copied and the copying takes place.

The drive wheels on the main shaft 70 are a pair (or more) of wheels 44and a center wheel 51. The wheel 51 is rubber so as to provide a strongpull on the paper when it is in the bite between the wheel 51 and thecooperating wheel 55. These wheels are relatively firm and the forcebetween wheels 51 and 55 is high enough to pull the document 30 from thestack and overcome the drag of the feed/separation rollers 31 and 37.The wheels 44 are larger in diameter than wheel 51 and very soft, suchas the foam rubber used in upholstery padding. The larger diameterallows the wheels 44 to touch the glass, while the wheel 51 does not.The wheels 44 move the paper, without skewing, on-to and off-of theglass and, as only single sheet is being moved, the force can be low.Wheels 44 may be about 6" apart.

After the copying is finished, the drive wheels 44 and 51 are caused torotate in the opposite direction (as shown by the arrow 35) and thesheet which was on the copier glass is driven around the drive wheels 44and 51 (in direction of arrow 46) and deposited in the receiving tray36.

With a center feed and separator, a center set of pull-out rollers 51and 55 is needed, and it is preferred to have them driven at a speedfaster than the feed from roller 31, and to have a one-way clutch 43 onthe feed roller shaft 74 so it will turn freely as the sheet is pulledthrough the drive. If there is a document in the bite of rollers 51 and55, these rollers pull the tail of the document through the bite ofrollers 31 and 37, causing rollers 31 and 37 to roll at a higher speedthan if driven by the motor 120, (as allowed by the one-way clutch 38).

The feeder drive is reversed by the reversal of the power polarity tothe motor 120. All of the system then goes in the reverse directionEXCEPT that beyond the one-way drive 43. These parts (shafts 74 and 72,rollers 31 and 37, gear-train 122, and the slip clutch 38) are drivendirectly by the motor 120 in the feed direction through the one-waydrive, but not in the reverse direction. The reverse roller system is avery good way to feed one and only one sheet even when the documents inthe stack are of different weights and have different surface finishes.Many of the common feed systems do not work satisfactorily as a bottomfeeder because of the weight and drag of the documents above the sheetto be fed. This drag also causes multi-feeds.

One or more separation rollers 37, as shown particularly in FIGS. 3, 6,7, and 9 operate to insure that only the bottom-most sheet 30 in thestack 28 is fed into the copying position.

The principle is simple, elegant and has wide tolerance, as shownparticularly in FIGS. 6 and 7. If one assumes likely values of 300 g. offorce between the feed roller 31 and separation rollers 37, acoefficient of friction of 1.2 for rubber to paper, or rubber to rubber,and a coefficient of 0.3 for paper to paper, the drive force of the feedroller 31 on the bottom of the bottom sheet 30 is 300×1.2=360 g. If twosheets are in the bite of the rollers 31 and 37, the force between themis still 300 g., but as the friction coefficient is only 0.3, thefriction force is only 300 g.×0.3=90 g. If the one-way clutch 38 is setto give a maximum force on the paper of any value from 90 g. to 359 g.,the system will function. Assume that the clutch is set to slip at 200g. force tangent to the surface of roller 37, the friction force of thepaper and roller is 360 g., but the force on the paper is limited to 200g. Therefore, when one document is being fed, the top roller 37 withroll on the paper and slip on the shaft 72. With two or more sheets, thesheet on the side of the drive wheel 31 is acted upon by a net drive of360-90 g.=270 g., and the sheet(s) not in contact with the drive roller31 are acted upon by a force of 90-200=110 g. (the negative sign showsthat the force is in the reverse direction, i.e., up and to the right)as shown in FIGS. 6 and 7 and the upper sheet(s) move back out of thebite. With one sheet in the bite, the net drive is 360 g.-200 g.=160 g.and the sheet is driven forward. With no paper in the bite, the feedroller 31 drives the retard roller 37 in the direction of arrow 61.

Other feed/separation systems which may be used are a high coefficientof friction feed roller 39 with a moderate coefficient retard member 62as shown in FIG. 5, or the wheel-and-fence system shown in FIG. 8. Herethe extra sheets are not pushed back, but they are kept from feedingforward.

Other well-known feed/separator systems could also be used, such as asticky-tape system marketed by the 3M Company.

The sheet 30 is slid onto the glass 112 with the two spacedguide-rollers 44 to prevent skewing. The drive should be light enough tomove the paper until it hits the end stop 34. The rollers can slip onthe paper if the normal force is low, or a weak drive may be used, suchas weak motor or another slip clutch.

A gate 45 is placed in the path so that when the sheet is returned bythe reversal of the rollers 44 and 51, the paper is directed to thestacking tray 36 in direction of arrow 46.

A photocell and light 48 indicates when there is a sheet in position atthe stops 34.

The photocell 48 may be a mechanical switch so that the light of thecopier does not affect it. It may not be needed because the motor 120can be driven long enough to be certain that the paper is at the stop34. But it is preferred to have such a signal so that the logic knowsthat the paper is at the stop readied to be copied. The switch can alsobe used to indicate when the last sheet had been fed. The logic would bearranged so that when there is no signal two seconds after a FEED, a"beep" is sounded, and a light is illuminated to advise the operator topick up the documents and/or to stop the copier.

With one drive motor 120 powering all the automatic document feeder onthe in-feed, there is a need to stop the feeding after the sheet hasreached the registration stop 34, and before the next sheet has reachedthe gate area 45. If the feed motion is stopped too soon, the firstsheet will not be registered on the glass; if too late, the lead edge ofthe second sheet will hit the first sheet as it exits, or it will havepushed down the gate so that the exiting of the first sheet is notdiverted into the stacking area 46. Either way there will be a jam.

To solve these problems, the surface speed of the main drive rollers 55and 44 must be much faster than the surface speed of the feed roller 31.Furthermore, the switch 48 detects the lead edge of the sheet as it isnear the end of its path which is the registration end stop 34.

The preferred design has a thin steel stripper 49 resting on the glass112 to strip the sheet from the glass when the rollers 44 and 51 rotatein direction of the arrow 35. The edge of the stripper 49 on the glass112 must be sharp so the edge of the paper does not stub against it. Thesharp edge may be guarded when the tray 23 is folded or when the entirefeeder 21 is lifted from the glass of the copier 102.

The logic of the feeder can either be in the copier when the feeder andcopier are connected, or in the feeder where there is no electricalinterface. In the case where the feeder has all the logic there may be aphotocell 136 near the center of the bottom 24, or at an edge or corner,to detect the motion of the copier scan lamp. The photocell 136 willthen note the passage of the light from the copier scan lamp, and soonafter the light passes the center of the feeder, the copying iscompleted, and it is time to remove one sheet from the glass and put onthe next sheet. Some copiers keep the lamp "ON" for the backstroke, somedo not. With the lamp "ON" on the backstroke, the feeder would be set torespond to every other light signal.

For some uses, it will be desirable to keep the sheet on the glass whileseveral copies are made. Thus, if four copies of a three-page documentare needed, the three-page document 28 is placed face-up in the tray23-a and, with an interfaced unit, the copier would be set for "4copies" and the "Print" button pushed. This would cause the interfacedfeeder to feed the last document from the stack onto the glass. Thecopier would then make the four copies and on the backstroke between thefourth and fifth copies, the sheet would be removed and the next sheetput on the glass. Thereafter, the four copies are made, the documentsare changed, and more copies are made. At the end, the top sheet isremoved from the glass and placed in the stacking area 36, face-up, andon top.

The outer main drive rollers 44 are made of a very soft material so thattheir interference with the glass causes only the light force needed tomove the paper but not so much as to cause excessive drag. The centerroller 51 is of a smaller diameter so it does not touch the glass. Thedifference in diameter may cause paper stress as the paper curves aroundthe curved path defined by 121.

In the improved design shown in FIG. 15, the shaft 220 is driven by aspline 221 which matches and fits the internal spline 222 of the hub 223secured to shaft 70 by set screw 224. The left end of shaft 220 is freeto move vertically but not horizontally as confined by fixed guides 225of bearing plate 226 mounted on side frame 53. Also extending from 226are ribs 227 which limit the axial motion of shaft 220.

Rollers 44 and roller 51 can be the same diameter, and rollers 44 reston the paper, or the glass 112 if there is no paper there. The force islight, as determined by the weight of the part, and/or a spring load.There is a gap between the bottom of roller 51 and the paper or glass.The roller rubber tires 44 may be solid, strong material as the load onthe paper is not determined by the deflection on the material.

The action of the feeder of the present invention may be betterunderstood by the following description:

During the FEED operation, as the bottom sheet 30 of the set ofdocuments 28 is separated and fed to the glass 112, the motor 120through gears 122 drives the system in the direction of the arrows 32,61 and 50 on rollers 31, 37 and 51, respectively. Roller 55 is driven byroller 51 and always rolls with it. Sheet 30 is moved to the lower leftin FIG. 3 as the friction of roller 31 on the sheet 30 is higher thanthe slip-clutch setting of the retard roller 37. When the lead edge ofsheet 30 hits the top side of gate 45, it pushes it down and moves intothe bite of the rollers 51/55. These rollers are turning at a highersurface speed than the sheet as driven by wheel 31, and have a greaterpulling force. They thus pull the sheet out of the rollers 31/37 causingroller 31 to turn faster than it would have been driven. The document iscurved around by guides 121 and stripper 49 onto the copier glass 112.It passes under the rollers 44 which are in light contact with the glassnear the edges of the sheet. They move the sheet through the thin space26-a between the glass 112 and the bottom plate 24 of the feeder 21until the leading edge of the sheet hits the end stop 34. The rollers 44have such a light drive on the sheet that they slip until the motorstops, as signaled by the electric-eye switch 48. The document is nowpositioned on the copier glass and the copies can be made.

During the TAKE-OFF operation, the motor 120 reverses and the shaft 70drives rollers 44 and 51 in the direction of arrow 35 in FIG. 3. Sincethe rollers 44 are in contact with the sheet, the sheet is driven to theleft in FIG. 3 and diverted by the sharp edge of stripper 49 into thebite of rollers 51/55. As the gate is normally in the position shown inFIG. 3, the sheet is guided in direction of arrow 46 into the stackingtray 36.

A feeder of the type described will feed one sheet and, as the end ofthat sheet exits the feed/separation rollers 31/37, the next sheet willstart to feed. The sheets would be touching head to tail, but in thepresent invention, when the first sheet reaches the main drive rollers,it is pulled faster than it was fed. This faster down-stream feed willcreate a gap between the tail of the first sheet and the lead edge ofthe next. This gap will be larger if the main drive pull overcomes thedrag of the feed roller. The one-way clutch 38 on the drive shaft 72allows it to drive, but as the first sheet is pulled faster than thedrive, the drive roller 31 is free to turn faster. The gap between thetail of the first sheet and the lead edge of the next sheet, and thusthe speed difference, must be enough that the first sheet is moved tothe registration stop 34 before the next sheet, which starts to feedwhen the tail of the first is pulled from the feed rollers, reaches thegate area.

More than the theoretical gap must be allowed as the motor coast willmove the lead edge of the second sheet. Also, allowance must be made forpossible imperfect separation where the second speed is pulled into thefeed/separation bite 31/37.

For some copiers, it will be preferred to have a long spring stripper 49so that it extends under the left edge of a sheet 30 when on the glass112. Thus the stripping of the sheet from the glass is not needed,because the left end was not resting on the glass. This will be best oncopiers which do no copy that edge of the document, and thus the end ofstripper 49 will not be seen on the copy.

When there is already a sheet on the glass, the TAKE-OFF operationprecedes the FEED operation.

As shown in FIG. 9, the motor 120 drives a belt 123. This belt drivesshafts 70 and 74 in the FEED direction. Due to the pulley and rollersizes, the surface speeds of the rollers 44 and 51 are much greater thanthat of the roller 31. When the motor is reversed, only shaft 70 isdriven directly by the motor due to the one-way clutch 43 on shaft 72.

While a reflective photoswitch can be used for the paper switch 48, thisrequires electronics and could be confused by the bright light of thecopier. A mechanical switch is preferred.

The novel design is for a very light force paper switch which rests onthe glass. This requires a flag having a close tolerance as the paper isthin and weak and may be very close to the glass. The freedom of theflag to rest on the glass under the effect of gravity and/or springpressure, in spite of mechanical tolerance of the parts or theirwarpage, is novel.

Two embodiments of the switch are shown in FIG. 13 and FIG. 14. Thestandard snap switch 201 is operated by the pivoted metal flag 203 whichis pivoted on shaft 205 which is welded to the flag and is free to movevertically in slots 207 in the fixed holder 209. It is shown in its homeposition at 203 and in its deflected position as 204. The sketch alsoshows the bevel 208 on the bottom of the flag so that a sheet of paperdoes not get under the flag. This design assures that the sharp edge ofthe flag is lightly on the glass, but free to move in response to theedge of the paper. The flag is returned to its normal position by thespring of the switch.

As the paper hits the flag with a considerable velocity, and as the flagneeds to move with the paper and along the glass, there is sometimes atendency for the flag to hop up and for the paper to slide under. Thismode of failure can be eliminated by a light spring force downward onthe flag, shown as springs 206.

FIG. 14 shows an alternate design which can be used where added headroomis available. The spring of the switch both returns the flag and addsthe downward spring force needed on the flag.

FIGS. 17 and 18 show another design wherein the feet 210 and 211 of theflag 212 are pivoted at 213 so that the bottom of the feet always slidethe glass plate and prevent the sheet from slipping beneath the flag.

FIG. 10 illustrates the gears connecting shafts 74 and 72. The shaft 72turns slower than shaft 74, as shown by the gear train 124. This savespower and permits use of a smaller motor. A belt can also be used. Theshafts 72 and 74 are driven in the same direction as shown by arrows 50.Roller 37 is loaded against roller 31 with a known and constant force.This can be caused by a built-in interference of the rollers, dependingon the softness of the rollers, or the bending of the shafts, todetermine the force. The ends of shaft 72 may be guided in slots 52 inframe 53 (as shown in FIGS. 5 and 9) and loaded with a light spring (notshown) in direction of arrow 54.

FIGS. 4 and 11 shows the feeder 21 on a copier 102 with a control panel104, a cover 110, and a registration edge 108 and 118 around glass 112.The feeder 21 is positioned to insure that the document, when on theglass 112 and at the stops 34, is where the copier needs the document tobe located for a proper copy to be made. A flange 100 fits between thelower edges of the feeder 21 and the edge 108 to hold the feeder inplace, to block the light, and to provide a white surface on the copierglass.

EXAMPLE

In the present invention, the lead edge of the first sheet moves about2" from the feed/separator rollers 31/37 and is then gripped by thepinch of the main shaft roller 51 and its idler roller 55. The mainroller pulls the sheet from the feed/separator bite, aided by theone-way clutch 38. With the customary 11" long paper, the main rollermust move the lead edge of the paper about 13" to reach the registrationstop; i.e., the 11" length and an added 2" around the main drive rollerwhich gets the tail of the sheet on the glass. This motion must be doneas the next sheet, which is being fed by the feed/separator rollers,moves toward the gate area. The next sheet can move about 3/4" beforethere is any interference.

Thus, using the above figures, the limiting case for the minimum excessspeed of the main drive over the feed drive is that the main drive mustmove the paper 13" before the lead edge of the next sheet moves 3/4"past the feed roller. The feed roller will not start to feed the secondsheet until the tail of the first sheet has been pulled free of theroller, assuming the separation is perfect. Thus the main drive mustmove the first sheet the 2" to the registration edge before the secondsheet moves the 3/4" to the gate area. The main drive must be over 2.7times as fast as the feed. (Ratio=2/0.75=2.6666 . . . )

In this embodiment with 0.75" diameter feed roller, a 1.4" diameter maindrive roller, and a belt drive with a speed ratio of 3.33 faster maindrive to feed drive, the main drive ratio is 6.2: i.e., comfortably overthe minimum and allowing for motor coast and the occasional imperfectseparation where the next sheet may be dragged by the first. The advanceof the second sheet past the feed roller is about 0.6" with a quick-stopcircuit on the motor. (As a check, the calculated motion with a 6.2ratio is 2/6.2=0.32". The paper feed speed, before the main drive pullsthe sheet, is about 6" per second at the normal 36 v. This suggests adelay of the quick-stop relay and the stopping of the motor of 46 ms, areasonable number.)

It is to be understood that the present invention may be embodied inother specific forms without departing from the spirit or specialattributes hereof, and it is therefore desired that the presentembodiments be considered in all respects as illustrative, and thereforenot restrictive, reference being made to the appended claims rather thanto the foregoing description to indicate the scope of the invention.

Having thus described by invention, what I claim as new and desire toprotect by Letters Patent are the following:
 1. In a document feeder fora copying device having an image glass, a stop member including:a frameadapted to be supported above the image glass, a stop member supportedby said frame and depending therefrom in the path of a document fed ontothe said image glass, said stop member including a switch and a flag,said flag disposed to turn on the switch in one position and to turn offthe switch in another position, said flag moved from one position to theother by a document fed onto the said image glass, and said flag havingone portion in contact with the said image glass, the portion of saidflag in contact with the image glass being a sharply beveled end, aswitch, including a spring, actuating the switch and urging the portionof the flag into contact with the image glass, said flag including atleast one pivotable foot which is in contact with the image glass.